IP Subnet Calculator
FreeCalculate network address, broadcast, and host range from an IP and CIDR, instantly.
Runs entirely in your browser. Nothing you enter is uploaded or stored.
Bold bits are the network portion (the first 24 bits, shared by every address in this subnet); the rest are host bits, free to vary across the 256 addresses in the block.
| Network | Host range | Broadcast | Usable hosts |
|---|---|---|---|
| 192.168.1.0/26 | 192.168.1.1 – 192.168.1.62 | 192.168.1.63 | 62 |
| 192.168.1.64/26 | 192.168.1.65 – 192.168.1.126 | 192.168.1.127 | 62 |
| 192.168.1.128/26 | 192.168.1.129 – 192.168.1.190 | 192.168.1.191 | 62 |
| 192.168.1.192/26 | 192.168.1.193 – 192.168.1.254 | 192.168.1.255 | 62 |
How it works
What does CIDR notation mean?
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a slash and a prefix length, like 192.168.1.0/24 — the prefix length says how many of the address's 32 bits are the fixed "network" portion, with the rest free to vary as "host" addresses within that network. A /24 fixes the first 24 bits (the first three octets), leaving the last 8 bits — 256 possible values — for hosts. A smaller number after the slash means a bigger network (more host bits); a bigger number means a smaller network.
What do network address, broadcast address, and usable hosts actually mean?
The network address is the first address in the block (all host bits zero) — it identifies the subnet itself, not a specific device. The broadcast address is the last one (all host bits one) — sending to it reaches every device on that subnet. Usable hosts is the count of addresses actually assignable to devices, which for most subnets is the total address count minus 2 (excluding the network and broadcast addresses). Two special cases don't follow that rule: a /31 (RFC 3021) has no network or broadcast address at all — both of its 2 addresses are usable, meant for point-to-point links — and a /32 identifies exactly one single host, with no range at all.
What is a subnet mask, and how is it different from CIDR?
They're two ways of expressing the same thing. A subnet mask (like 255.255.255.0) is the network portion written out as its own dotted-decimal address — wherever the mask has a 255, that whole byte is network; CIDR notation (/24) just states the count of leading 1 bits instead. This tool accepts either and converts between them automatically.
Is anything I enter here sent anywhere?
No — every calculation happens locally in your browser.